University of North Texas

About: University of North Texas is a education organization based out in Denton, Texas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 11866 authors who have published 26984 publications receiving 705376 citations. The organization is also known as: Fight, North Texas & UNT.

Improving the efficiency of water splitting in dye-sensitized solar cells by using a biomimetic electron transfer mediator

Abstract: Photoelectrochemical water splitting directly converts solar energy to chemical energy stored in hydrogen, a high energy density fuel. Although water splitting using semiconductor photoelectrodes has been studied for more than 40 years, it has only recently been demonstrated using dye-sensitized electrodes. The quantum yield for water splitting in these dye-based systems has, so far, been very low because the charge recombination reaction is faster than the catalytic four-electron oxidation of water to oxygen. We show here that the quantum yield is more than doubled by incorporating an electron transfer mediator that is mimetic of the tyrosine-histidine mediator in Photosystem II. The mediator molecule is covalently bound to the water oxidation catalyst, a colloidal iridium oxide particle, and is coadsorbed onto a porous titanium dioxide electrode with a Ruthenium polypyridyl sensitizer. As in the natural photosynthetic system, this molecule mediates electron transfer between a relatively slow metal oxide catalyst that oxidizes water on the millisecond timescale and a dye molecule that is oxidized in a fast light-induced electron transfer reaction. The presence of the mediator molecule in the system results in photoelectrochemical water splitting with an internal quantum efficiency of approximately 2.3% using blue light.

Private label brand image: its relationship with store image and national brand

Abstract: Purpose – The purpose of empirical study is to focus on the relationship between perceived private label brand (PLB) image, and perceived store image (SI) and feeling associated with the presence of national brand (NB).Design/methodology/approach – The data are collected using a self administered questionnaire from respondents belonging to generation Y in their 20s. The focal product was apparels sold at department stores.Findings – The results indicate that the store atmosphere and store quality positively influence the perception of PLB's quality, whereas, the congruence between national brand and store image (NBSI) has a negative influence on PLB's quality. In comparison, the store quality, store convenience, store price/value, and the congruence between NB and PLB have a positive influence on the affective dimension of the PLB image, whereas, the congruence between NBSI has a negative influence.Research limitations/implications – A key limitation of this study is the sampling frame. Future studies sho...

Code Mixing: A Challenge for Language Identification in the Language of Social Media

Abstract: In social media communication, multilingual speakers often switch between languages, and, in such an environment, automatic language identification becomes both a necessary and challenging task. In this paper, we describe our work in progress on the problem of automatic language identification for the language of social media. We describe a new dataset that we are in the process of creating, which contains Facebook posts and comments that exhibit code mixing between Bengali, English and Hindi. We also present some preliminary word-level language identification experiments using this dataset. Different techniques are employed, including a simple unsupervised dictionary-based approach, supervised word-level classification with and without contextual clues, and sequence labelling using Conditional Random Fields. We find that the dictionary-based approach is surpassed by supervised classification and sequence labelling, and that it is important to take contextual clues into consideration.

On the Transfer of Parametric Values in L2 Development

Abstract: White (e.g., 1990/1991; 1992a) argued that grammatical representations in second-language development can be understood in terms of parametric values that are transferred from the learner's native language. Schwartz (1993a; 1993b) and Schwartz and Sprouse (1994) push this view of transfer to its logical limit: The initial state of L2 acquisition is determined in its entirety by the parametric values of the native language. This article presents early-stage learner data that are not compatible with this strong view of parametric transfer. An alternative proposal is made, a weak transfer view in which lexical and functional projections transfer, and the headedness of those projections transfers, but morphology-driven values of features like the strength of agreement do not transfer. This idea is checked against learner data and is also evaluated for the extent to which it follows in a principled fashion from linguistic theory.